Antenna beam management for multi-connection communications

ABSTRACT

Antenna beam sweeping according to the present disclosure involves different communication devices that are within an interference range of each other transmitting beam sweeping signals using different communication resources. This allows a receiver to distinguish between beam sweeping signals that are received from different transmitters, and may facilitate antenna beam alignment in multi-connection scenarios. Beam indices could be used to identify antenna beams for antenna beam management, in control signaling between base stations and User Equipment (UE), for example. Beam tracking and other aspects of antenna beam management are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/403,638 filed on Jan. 11, 2017, the entire contents of bothof which are incorporated herein by reference.

FIELD

The present disclosure relates generally to wireless communications and,in particular, to management of antenna beams in multi-connectioncommunications.

BACKGROUND

Some wireless communication systems, such as proposed 5G New Radio (NR)systems, support High Frequency (HF) communications using highlydirectional, narrow antenna beams. Determining antenna beam directionsfor establishing communications and subsequently maintainingcommunications using narrow antenna beams can be a challenge, especiallyin multi-connection scenarios in which a User Equipment (UE) hasconnections to multiple base stations or a base station has connectionswith multiple UEs.

SUMMARY

Antenna beam alignment in a multi-connection scenario could be moreeffective if a communication device that receives antenna beam sweepingsignals is able to distinguish between beam sweeping signals that arereceived from different transmitters. For example, differentcommunication devices could use different communication resources totransmit beam sweeping signals, and a receiving device may, based on thedifferent communication resources, distinguish between beam sweepingsignals that are received from the different communication devices.

According to an aspect of the present disclosure, a method involvesdetermining a first communication resource that is to be used fortransmission of a first beam sweeping signal by a first communicationdevice. The first communication resource is different from a secondcommunication resource for transmission of a second beam sweeping signalby a second communication device that is within an interference range ofthe first communication device. The method also involves transmittingthe first beam sweeping signal from the first communication device usingthe first communication resource and a plurality of antenna beams thatare oriented in a plurality of directions. The first communicationdevice could be a base station or a UE.

Feedback to the first communication device is provided in someembodiments. The first communication device could monitor for receipt ofan indication, from a third communication device that receives the firstbeam sweeping signal, of one direction of the plurality of directionsfrom which the third communication device best received the first beamsweeping signal. The indication could be an explicit indication of theone direction, or an implicit indication from which the firstcommunication device determines the one direction.

A method could also involve establishing a connection with the thirdcommunication device via an antenna beam of the plurality of antennabeams that is oriented in the one direction.

In an embodiment, the first communication device is a base station andthe third communication device is a UE, and the method involvesrepeating the transmitting and monitoring to track movement of the UE.Another form of such beam tracking involves monitoring, at the basestation, the plurality of antenna beams for receipt of a third beamtracking signal from the UE; and transmitting to the UE an indication ofa further direction from which the base station best received the thirdbeam tracking signal from the UE.

The base station could transmit to the UE a signal to cause the UE toinitiate a beam tracking procedure that involves transmitting the thirdbeam tracking signal from the UE and monitoring at the UE for receipt ofthe indication of the further direction from the base station.

In an embodiment, the first communication resource and the secondcommunication resource are part of a set of orthogonal communicationresources. A set of communication resources that includes the firstcommunication resource and the second communication resource could alsoor instead be a set of time division multiplexed communicationresources, a set of frequency division multiplexed communicationresources, or a set of code division multiplexed communicationresources.

Another aspect of the present disclosure provides a method that involvesreceiving at a communication device, using a plurality of antenna beamsthat are oriented in a plurality of directions, a first beam sweepingsignals from a first transmitting communication device in a firstcommunication resource and a second beam sweeping signal from a secondtransmitting communication device in a second communication resourcethat is different from the first communication resource. The method alsoinvolves determining, based on the first communication resource, a firstdirection of the plurality of directions from which the first beamsweeping signal is best received from the first transmittingcommunication device, and determining, based on the second communicationresource, a second direction of the plurality of directions from whichthe second beam sweeping signal is best received from the secondtransmitting communication device.

The method may also involve determining, based on the firstcommunication resource, a first transmit direction in which the firstbeam sweeping signal was transmitted by the first transmittingcommunication device; determining, based on the second communicationresource, a second transmit direction in which the second beam sweepingsignal was transmitted by the second transmitting communication device;and transmitting an indication of the first transmit direction to thefirst transmitting communication device and an indication of the secondtransmit direction to the second transmitting communication device. Theindications could be explicit indications of the first transmitdirection and the second transmit direction or implicit indications fromwhich the first transmitting communication device determines the firsttransmit direction and the second transmitting communication devicedetermines the second transmit direction.

In an embodiment, the method provides for downlink beam sweeping, inwhich the communication device is a UE and the first and secondtransmitting communication devices are base stations. A third beamtracking signal could be transmitted from the UE using the plurality ofantenna beams, and monitoring could then be performed at the UE forreceipt of an indication, from a base station, of a further direction ofthe plurality of directions from which the base station best receivedthe third beam tracking signal from the UE.

Monitoring could also be performed at the UE for receipt of a signal,from the base station, to cause the UE to initiate a beam sweepingprocedure that involves transmitting the third beam tracking signal fromthe UE and monitoring for receipt of the indication of the furtherdirection from the base station.

Antenna beam sweeping could involve both transmit-side operations andreceive-side operations. According to a further aspect of the presentdisclosure, a method involves: determining different communicationresources to be used for transmission of beam sweeping signals by aplurality of base stations that are within an interference range of eachother in a communication network; transmitting the beam sweeping signalsfrom the plurality of base stations using the different communicationresources and a plurality of antenna beams, at each of the basestations, that are oriented in a first plurality of directions;monitoring, at a UE, a plurality of antenna beams that are oriented in asecond plurality of directions for receipt of beam sweeping signals fromthe plurality of base stations in the different communication resources;and determining at the UE, for each of the base stations from which abeam sweeping signal is received and based on the differentcommunication resources, one direction of the second plurality ofdirections from which the received beam sweeping signal is best receivedfrom the base station.

In an embodiment, the UE provides feedback to each of the base stationsfrom which a beam sweeping signal is received, by determining at the UE,based on the different communication resources, a transmit direction inwhich the received beam sweeping signal was transmitted by the basestation, and transmitting from the UE to the base station an explicit orimplicit indication of the determined transmit direction.

According to a further aspect, a non-transitory processor-readablemedium stores instructions which, when executed by one or moreprocessors, cause the one or more processors to perform a method asdisclosed herein.

Apparatus embodiments are also disclosed. For example, a communicationdevice could include an antenna array, a transmitter operatively coupledto the antenna array; a receiver operatively coupled to the antennaarray; and an antenna beam manager operatively coupled to thetransmitter and to the receiver.

The transmitter could be configured to form a plurality of antenna beamsthat are oriented in a plurality of directions, and the antenna beammanager could be configured to: determine a first communication resourceto be used for transmission of a first beam sweeping signal by thecommunication device, with the first communication resource beingdifferent from a second communication resource for transmission of asecond beam sweeping signal by a second communication device that iswithin an interference range of the first communication device; andtransmit the first beam sweeping signal via the transmitter using thefirst communication resource and the plurality of antenna beams.

In some embodiments, the antenna beam manager is further configured tomonitor the receiver for receipt of an indication, from a thirdcommunication device that receives the first beam sweeping signal, ofone direction of the plurality of directions from which the thirdcommunication device best received the first beam sweeping signal. Theindication could be an explicit indication of the one direction or animplicit indication from which the communication device determines theone direction.

The receiver could be configured to form a plurality of receive antennabeams that are oriented in a plurality of receive directions, and theantenna beam manager could be configured to: receive, using theplurality of receive antenna beams, a first beam sweeping signal from afirst transmitting communication device in a first communicationresource and a second beam sweeping signal from a second transmittingcommunication device in a second communication resource that isdifferent from the first communication resource; determine, based on thefirst communication resource, a first direction of the plurality ofdirections from which the first beam sweeping signal is best receivedfrom the first transmitting communication device; and determine, basedon the second communication resource, a second direction of theplurality of directions from which the second beam sweeping signal isbest received from the second transmitting communication device. Theantenna beam manager could be further configured to: determine a firsttransmit direction in which the first beam sweeping signal wastransmitted by the first transmitting communication device; determine,based on the second communication resource, a second transmit directionin which the second beam sweeping signal was transmitted by the secondtransmitting communication device; and transmit via the transmitter anexplicit or implicit indication of the first transmit direction to thefirst transmitting communication device and an explicit or implicitindication of the second transmit direction to the second transmittingcommunication device.

A communication device as described above and elsewhere herein could beimplemented as a base station or as a UE. An antenna beam manager at abase station and/or at a UE could be further configured to perform beamtracking to track movement of the UE.

Antenna beam management could involve antenna beam information such asbeam indices and/or beam directions, and possibly other information suchas UE identifiers, base station identifiers, and/or connectionidentifiers. A memory could be operatively coupled to an antenna beammanager, and the antenna beam manager could be further configured tostore to the memory a beam index associated with any of the directionsreferenced above, and/or other information.

According to a further aspect, a communication network includes aplurality of base stations and one or more UEs.

In an embodiment, each of the base stations includes: a base stationantenna array; a base station transmitter, operatively coupled to thebase station antenna array, to form a plurality of base station antennabeams that are oriented in a first plurality of directions; a basestation receiver operatively coupled to the base station antenna array;and a base station antenna beam manager, operatively coupled to the basestation transmitter and to the base station receiver, to: determine acommunication resource to be used for transmission of beam sweepingsignals by the base station, the communication resource being differentfrom communication resources for transmission of beam sweeping signalsby other base stations that are within an interference range of the basestation; and transmit the beam sweeping signal from the base stationtransmitter using the determined communication resource and theplurality of base station antenna beams.

Each UE could include: a UE antenna array; a UE transmitter, operativelycoupled to the UE antenna array; a UE receiver operatively coupled tothe UE antenna array, to form a plurality of UE antenna beams that areoriented in a second plurality of directions; and a UE antenna beammanager, operatively coupled to the UE transmitter and to the UEreceiver, to: receive, using the plurality of UE antenna beams, a firstbeam sweeping signal from a first base station in a first communicationresource and a second beam sweeping signal from a second base station ina second communication resource that is different from the firstcommunication resource; determine, based on the first communicationresource, a first direction of the second plurality of directions fromwhich the first beam sweeping signal is best received from the firstbase station; and determine, based on the second communication resource,a second direction of the plurality of directions from which the secondbeam sweeping signal is best received from the second base station.

In such a communication network, the UE antenna beam manager could befurther configured to: determine, based on the first communicationresource, a first transmit direction in which the first beam sweepingsignal was transmitted by the first base station; determine, based onthe second communication resource, a second transmit direction in whichthe second beam sweeping signal was transmitted by the second basestation; and transmit an explicit or implicit indication of the firsttransmit direction to the first base station and an explicit or implicitindication of the second transmit direction to the second base station.

Other aspects and features of embodiments of the present disclosure willbecome apparent to those ordinarily skilled in the art upon review ofthe following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described in greater detail withreference to the accompanying drawings.

FIG. 1 is a block diagram illustrating a communication system.

FIG. 2 is a block diagram illustrating downlink antenna beam sweeping.

FIG. 3 is a block diagram illustrating downlink antenna beam sweeping inwhich multiple base stations use the same communication resources.

FIG. 4 is a block diagram illustrating downlink antenna beam sweeping inwhich multiple base stations use different communication resources.

FIG. 5 is a block diagram illustrating uplink antenna beam sweeping.

FIG. 6 is a block diagram illustrating uplink antenna beam sweepingbetween a UE and multiple base stations.

FIG. 7 is a block diagram illustrating uplink antenna beam sweeping inwhich multiple UEs use different communication resources.

FIG. 8 is a block diagram illustrating antenna beam management usingfixed beam indices.

FIG. 9 is a block diagram illustrating transmission control according toan embodiment.

FIG. 10 is a block diagram illustrating transmission control accordingto another embodiment.

FIG. 11 is a block diagram illustrating transmission patterns inaccordance with a further embodiment.

FIG. 12 is a flow diagram illustrating a method according to anembodiment.

FIG. 13 is a flow diagram illustrating an example method according to afurther embodiment.

FIG. 14 is a block diagram illustrating an example base station.

FIG. 15 is a block diagram illustrating a UE according to an embodiment.

FIG. 16 is a block diagram illustrating a communication device withmultiple Radio Frequency (RF) chains.

DETAILED DESCRIPTION

For illustrative purposes, specific example embodiments will now beexplained in greater detail below in conjunction with the figures.

The embodiments set forth herein represent information sufficient topractice the claimed subject matter and illustrate ways of practicingsuch subject matter. Upon reading the following description in light ofthe accompanying figures, those of skill in the art will understand theconcepts of the claimed subject matter and will recognize applicationsof these concepts not particularly addressed herein. It should beunderstood that these concepts and applications fall within the scope ofthe disclosure and the accompanying claims.

Moreover, it will be appreciated that any module, component, or devicedisclosed herein that executes instructions may include or otherwisehave access to a non-transitory computer/processor readable storagemedium or media for storage of information, such as computer/processorreadable instructions, data structures, program modules, and/or otherdata. A non-exhaustive list of examples of non-transitorycomputer/processor readable storage media includes magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,optical disks such as compact disc read-only memory (CD-ROM), digitalvideo discs or digital versatile discs (i.e. DVDs), Blu-ray Disc™, orother optical storage, volatile and non-volatile, removable andnon-removable media implemented in any method or technology,random-access memory (RAM), read-only memory (ROM), electricallyerasable programmable read-only memory (EEPROM), flash memory or othermemory technology. Any such non-transitory computer/processor storagemedia may be part of a device or accessible or connectable thereto.Computer/processor readable/executable instructions to implement anapplication or module described herein may be stored or otherwise heldby such non-transitory computer/processor readable storage media.

Turning now to the figures, some specific example embodiments will bedescribed.

FIG. 1 is a diagram illustrating a communication system. Thecommunication system 100 includes a core network 102 and an accessnetwork 106.

The core network 102 may provide any of various services, such as callcontrol/switching and gateways to other networks. The core network 102includes network components such as routers, switches, and servers.

The access network 106 is a wireless communication network, and isconnected or coupled to the core network 102. The base stations or nodes108 a, 108 b, 108 c, 108 d, 108 e provide wireless communication servicewithin wireless coverage areas 110 a, 110 b, 110 c, 110 d, 110 e. Eachbase station 108 a-e may be implemented using a radio transceiver, oneor more antennas, and associated processing circuitry, such as antennaradio frequency (RF) circuitry, analog-to-digital/digital-to-analogconverters, etc. Transmit-Receive Points (TRPs), evolved NodeBs (eNBs),and other types of network nodes and network equipment are examples ofthe base stations 108 a-e.

UEs 104 a, 104 b, 104 c, 104 d wirelessly access the communicationsystem 100 using the access network 106. Each UE 104 a-d includes aradio transmitter and a radio receiver which may be integrated into aradio transceiver, one or more antennas, and associated processingcircuitry, such as antenna radio frequency (RF) circuitry,analog-to-digital/digital-to-analog converters, etc. The base stations108-e and the UEs 104 a-d may include similar types of components tosupport communications with each other in the communication system 100,but the actual implementations may be different. For example, the UEs104 a-d are portable between locations, whereas the base stations 108a-e are typically intended to be installed at a fixed location.

The base stations 108 a-e are connected to a centralized processingsystem 120 in the access network 106, via communication links 112 a, 112b, 112 c, 112 d, 112 e. Each communication link 112 a-e is an opticalfibre communication link in one embodiment. Each base station 108 a-eincludes circuitry for transmitting data to the centralized processingsystem 120 and for receiving data from the centralized processing systemvia its communication link 112 a-e. Although shown as a singlecentralized processing system in FIG. 1, the centralized processingsystem 120 may be implemented by a network of one or more processing andcontrol servers. Alternatively, the centralized processing system 120may be implemented as a single server.

The base stations 108 a-e may serve as a gateway between wireline andwireless portions of the access network 106, although this need not bethe case in embodiments in which the communication links 112 a-e arewireless links. The base stations 108 a-e may be placed at fixedlocations by a network provider, for example, to provide a substantiallycontinuous wireless coverage area. This is shown in FIG. 1 in thatwireless coverage areas 110 a-e overlap each other so that the UEs 104a-d may move throughout the wireless coverage areas and still be servedby the access network 106.

Effects such as free space path loss, for example, may limit the rangeof HF wireless connections. Highly directional antenna beams mayincrease HF connection range, and could be used between any of the basestations 108 a-e and any of the UEs 104 a-d for which HF communicationsare to be supported. In NR, for example, highly directional antennabeams having a beam width with 10 degree half-power bandwidth could beused for HF communications at frequencies above 6 GHz. This beam widthand HF range are provided solely as illustrative examples. The presentdisclosure is not limited to management of antenna beams in this examplebeam width range or to communications within this example HF range.

Antenna beam management as disclosed herein encompasses initial accessto establish communications and subsequent actions to maintaincommunications. Initial access involves antenna beam sweeping toestablish alignment of transmit (Tx) and receive (Rx) antenna beams foreach connection. Beam sweeping could include coarse alignment, alsoreferred to as initial beam training, using antenna beams that are widerthan those that will be used for communications. After alignment of theTx and Rx antenna beams is established, maintaining communications couldinvolve such actions as antenna beam tracking or refinement to updateand maintain alignment of antenna beam pairs as UEs move or wirelesspaths between UEs and base stations are affected by obstacles. Beamtracking after initial beam training, using narrower antenna beams forfine alignment, could also involve beam sweeping over a more limitedsweeping range

Embodiments of the present disclosure may be applicable to any ofvarious multi-connection scenarios, between multiple base stationsand/or multiple UEs. Initial antenna beam configuration, beam sweepingfor initial beam training and beam tracking, beam management, andtransmission control for multi-connection communications are disclosed.

FIG. 2 is a block diagram illustrating downlink antenna beam sweeping.In an embodiment, downlink antenna beam alignment involves transmissionof a beam sweeping signal by each base station. In FIG. 2 two TRPs, TRP1and TRP2, are shown as examples of base stations. Each TRP may transmita synchronization signal, for example. A synchronization signal is anexample of a beam sweeping signal that enables a UE to establish aconnection with a base station and thereby gain access to acommunication network. In another example, a beam reference signalinstead of a synchronization signal could be transmitted during beamsweeping.

In the example shown in FIG. 2, downlink beam sweeping involves the TRPstransmitting the same beam sweeping signal using n antenna beams thatare oriented in n directions. Each TRP transmits the same beam sweepingsignal in each of the n directions. A UE monitors for receipt of thebeam sweeping signal in each of k directions, using k antenna beams thatare oriented in the k directions. This involves a total of n*ktransmissions of the beam sweeping signal by each TRP in this example.

The antenna beam sweeping period shown in FIG. 2 includes k cycles. Ineach of the k cycles, each TRP transmits a beam sweeping signal in eachof the n antenna beam directions of the TRP, and the UE monitors forreceipt of a beam sweeping signal in one of k directions. In anotherembodiment, each TRP transmits a beam sweeping signal in one of the ndirections and the UE monitors each of the k directions for receipt of abeam sweeping signal in each of n beam sweeping cycles in a beamsweeping period.

Each of the TRPs transmits the beam sweeping signal in n directions inthe example shown in FIG. 2. In other embodiments, different TRPs mayhave different numbers of antenna beam directions. Although the TRPs andthe UE have different numbers of antenna beam directions in FIG. 2, insome embodiments n=k.

The optimal beam pairs labelled in FIG. 2 are discussed in furtherdetail below with reference to FIGS. 3 and 4.

FIG. 3 is a block diagram illustrating downlink antenna beam sweeping inwhich multiple base stations use the same communication resources. FIG.3, like FIG. 2, shows two TRPs 302, 304 and one UE 306. In FIG. 3, threeantenna beams b1, b2, b3 are shown for each TRP 302, 304, and fiveantenna beams B1, B2, B3, B4, B5 are shown for the UE 306. In thenotation of FIGS. 2, n=3 and k=5. There may be more or fewer antennabeams in other embodiments.

The UE 306 in FIG. 3 can potentially connect to TRP1 302 and TRP2 304.Signals transmitted from the TRPs 302, 304 may therefore interfere witheach other, and in this sense the TRPs are within an interference rangeof each other. If the TRPs 302, 304 transmit their beam sweeping signalsusing the same communication resources during an antenna beam sweepingperiod, then the UE 306 receives a combination of beam sweeping signalsfrom the TRPs. Communication resources are shown as time/frequencyresources in FIG. 3. When the TRPs 302, 304 use the same communicationresources, the UE 306 may detect a highest received signal strength inits antenna beam B3 direction when both of the TRPs 302, 304 aretransmitting in their beam b2 directions. TRP1 b2, TRP2 b2, and UE B3could be identified as the optimal group of TRP1, TRP2, and UE antennabeams, as shown in FIG. 2. However, this is based on a highest receivedsignal strength of a combination of beam sweeping signals from both ofthe TRPs 302, 304. Received signal strength and optimal antenna beamsand directions for a connection between the TRP1 302 and the UE 306could be different if TRP2 304 were not transmitting to the UE 306 usingthe same communication resources as TRP1 during beam sweeping. Receivedsignal strength and optimal antenna beams and directions for aconnection between the TRP2 304 and the UE 306 could also or instead bedifferent if TRP1 302 were not transmitting to the UE 306 using the samecommunication resources as TRP2 during beam sweeping.

In an embodiment, different base stations use different communicationresources to transmit beam sweeping signals during beam sweeping, toallow a UE to distinguish between beam sweeping signals that arereceived from the different base stations and to identify a preferredantenna beam direction for a connection with each of the base stations.The different communication resources could be separated by timeaccording to a Time Division Multiplexing (TDM) scheme, by frequencyaccording to a Frequency Division Multiplexing (FDM) scheme, by codingin a Code Division Multiplexing (CDM) scheme, or otherwise. In anembodiment, the different communication resources that are used bydifferent base stations to transmit beam sweeping signals are orthogonalto each other. Therefore, a set of communication resources that includesdifferent communication resources used by different communicationdevices within an interference range of each other could includeorthogonal communication resources, such as time division multiplexedresources, frequency division multiplexed resources, and/or codedivision multiplexed resources.

FIG. 4 is a block diagram illustrating downlink antenna beam sweeping inwhich multiple base stations use different communication resources. TheTRPs 402, 404 are examples of base stations, and a UE is shown at 406.

FIG. 4 also illustrates an FDM scheme 410 in which each TRP 402, 404uses different frequency resources 412, 414 at the same times totransmit their beam sweeping signals. According to a TDM scheme 420,each TRP 402, 404 uses the same frequency resources at different timesto transmit their beam sweeping signals. A CDM scheme is also shown at430, in which frequency/time resources are multiplexed by codes fortransmission of beam sweeping signals by the TRPs. These multiplexingschemes are examples, any of which could be used by the TRPs 402, 404 indifferent embodiments.

In some embodiments, serving base stations such as the TRPs 402, 404 canbe identified before initial beam alignment begins, and resourceplanning can be coordinated accordingly. For example, a communicationnetwork could include both Low Frequency (LF) and HF TRPs, and an LF TRPcould assist the UE 406 with initial antenna beam alignment. In anLF-assisted scenario, the UE 406 could first establish a connection withan LF-TRP. Antenna beam alignment and connection establishment with anLF TRP may be faster relative to antenna beam alignment and connectionestablishment with an HF TRP. This is because LF TRP antenna beams arenot as highly directional as HF TRP antenna beams and therefore are notas narrow as HF TRP antenna beams. Consequently, connectionestablishment with an LF TRP need not necessarily involve beam sweeping.An LF TRP could provide to the UE 406 information that identifies thenearby HF TRPs 402, 404 with which the UE may be able to connect, and/orinformation regarding HF TRP beam sweeping signal communication resourceallocations to enable to the UE to monitor for receipt of beam sweepingsignals from the HF TRPs.

In another example, if a communication network only includes HF TRPs, aUE could first establish a connection with an HF TRP, possibly withoutoptimal beam alignment in a downlink beam sweeping approach as shown inFIG. 3, in which the same communication resources are used in beamsweeping by different TRPs. An HF TRP could then provide to the UE 306information that identifies the nearby HF TRPs 302, 304 with which theUE may be able to connect, and/or information regarding HF TRP beamsweeping signal communication resource allocations. This may enable UEsand TRPs to transition to the beam sweeping approach illustrated in FIG.4, in which the HF TRPs 402, 404 again transmit beam sweeping signals,and the UE 406 monitors for receipt of beam sweeping signals from the HFTRPs to more accurately align the TRP and UE antenna beams.

LF TRPs could also or instead be involved in managing or distributingbeam sweeping signal communication resource allocations to HF TRPs 402,404. In communication networks in which only HF TRPs are implemented,beam sweeping signal communication resource allocations could be managedand distributed among HF TRPs with other network configurations orsettings.

With the TRPs 402, 404 using different communication resources totransmit beam sweeping signals to the UE 406 during beam sweeping, theUE is able to distinguish between beam sweeping signals that arereceived from each of the TRPs. The UE 402 can then determine one ormore received signal criteria, such as received signal strength, of abeam sweeping signal that is received from each TRP 402, 404. Based onthe one or more received signal criteria, the UE 402 can identify apreferred or optimal antenna beam direction for a connection with eachTRP 402, 404. With reference again to FIG. 2, an optimal antenna beampair for a connection between TRP1 and the UE includes TRP1 beam b1 andUE beam B1 in this example. Similarly, the optimal beam directions orbeam pair for a connection between TRP2 and the UE includes TRP2 beambn, with n=3 in the example shown in FIG. 4, and UE beam Bk, with k=5 inthe example shown in FIG. 4.

Selection of preferred or optimal antenna beams and directions is basedon the different communication resources and received signalcharacteristics, which are measured or otherwise determined at areceiver. For downlink beam sweeping as shown in FIG. 4, the UE 406 isthe receiver. The UE 406 distinguishes between the beam scanning signalsthat are received from TRP1 402 and TRP2 404 based on the differentcommunication resources that are used by the TRPs. The UE 406 couldmeasure received signal strength, or also or instead measure ordetermine other received signal characteristics, and identify the bestUE antenna beam or reception direction from which the UE best received abeam sweeping signal from each TRP 402, 404. This could be a receptiondirection from which the UE 406 measured the highest received signalstrength from each TRP 402, 404, for example. The UE 406 also determinesa corresponding TRP antenna beam or direction in which the received beamsweeping signal was transmitted. The UE 406 transmits to each of theTRPs 402, 404 an indication of at least the TRP antenna beam ordirection, corresponding to the best UE antenna beam or direction, inwhich the received signals were transmitted by each TRP.

The indication could be in any of various forms. A TRP 402, 404 couldinclude in its beam sweeping signal an explicit indication of the TRPantenna beam or direction in which the beam sweeping signal wastransmitted. The UE 406 could then include the same indication in aresponse to the TRP 402, 406 after the beam sweeping period ends. Anexplicit indication could be a beam index, such as a number from 1 to nfor the beam sweeping example in FIG. 2.

Implicit signalling is also contemplated. With reference to FIG. 2, forexample, each TRP could sequentially transmit a beam sweeping signal ineach of n directions during each cycle of the beam sweeping period, andthe UE may then identify the best reception direction based on the timeor position of the best received beam sweeping signal in the sweepingcycle. The transmit direction corresponding to the best receptiondirection could also or instead be reported to a TRP implicitly. Forexample, a TRP could derive the best beam sweeping signal transmitdirection from the timing of a signal in which the UE confirms receiptof a beam sweeping signal or otherwise provides a response to a beamsweeping signal. A confirmation of receipt and a response are examplesof an implicit indication of the best reception direction.

The downlink beam sweeping examples in FIGS. 2 to 4 involve a singlebeam sweeping period. In other embodiments, multiple stages of beamsweeping could be used. For example, an initial coarse antenna beamalignment stage could use wider antenna beams for coarse alignment, anda fine alignment stage could involve beam sweeping over a smaller rangeof directions with narrower, more highly directional antenna beams.

In an embodiment, TRPs send synchronization signals to UEs during beamsweeping, and a UE then initiates an initial access procedure bytransmitting a preamble to each TRP. A beam ID or other explicitindication of the best transmit antenna beam could be contained in thepreamble. An indication of the best transmit beam could be implicit. Forexample, a UE could transmit a preamble using communication resourcesthat are associated with the best transmit antenna beam of each TRP, toprovide an implicit indication to each TRP as to which of the TRP'stransmit beams is best for communications with the UE. A UE could, butneed not necessarily, provide to a TRP an indication of the best receiveantenna beam via which a beam sweeping signal was received from the TRP.

FIGS. 2 to 4 relate to downlink antenna beam sweeping and alignment.FIG. 5 is a block diagram illustrating uplink antenna beam sweeping Ifreciprocity holds in respect of antenna beam alignment at both a TRPside and a UE side of a connection, the uplink beam sweeping might notbe needed. Under a reciprocity condition, the best uplink antenna beamdirections at a TRP and a UE are the same as the best downlink antennabeam directions at the same TRP and UE. Otherwise, if reciprocity doesnot hold at either a TRP or a UE, then uplink beam sweeping could beused to determine the best uplink beam directions at a TRP and a UE.Similarly, downlink antenna beam scanning might not be performed ifantenna beam alignment has already been completed through uplink beamscanning, if reciprocity holds at both a TRP and a UE.

FIG. 5 is similar to FIG. 2, but in FIG. 5 the UE transmits a beamsweeping signal, which may include a predetermined sequence for example,and the TRPs monitor multiple antenna beam directions for reception ofthe beam sweeping signal. In an embodiment, UEs obtain the beam sweepingsignals used for uplink beam sweeping after connecting to a TRP throughdownlink beam sweeping. Uplink beam sweeping could instead beLF-assisted, with LF TRPs providing sequences to UEs, for example.

FIG. 6 is a block diagram illustrating uplink antenna beam sweepingbetween a UE and multiple base stations. If only one UE 606 isattempting to establish a network connection with the TRPs 602, 604,then no communication resource separation or multiplexing is needed, asshown at 608. A beam sweeping signal is transmitted only by the UE 606in this example, and each TRP 602, 604 is able to identify its bestreception direction for a connection with the UE.

FIG. 7 is a block diagram illustrating uplink antenna beam sweeping inwhich multiple UEs that are close to each other use differentcommunication resources. If multiple UEs 706, 708 attempt to access anetwork through connections with at least one common TRP 702, 704, as inFIG. 7, different communication resources are used by the UEs totransmit beam sweeping signals to the TRPs. An FDM scheme 710 is shownby way of example, in which the UEs 706, 708 use different frequencyresources 712, 714. The frequency bands assigned to each UE 706, 708 foruplink beam alignment or training could be signaled to the UEs from anLF-TRP, or from an HF-TRP during downlink beam sweeping, for example.TDM or CDM could be used in other embodiments, in which similarsignaling options could be implemented. Preferred or optimal antennabeam directions for each UE 706, 708, can then be identified by each TRP702, 704.

In FIG. 7, the TRPs 702, 704 receive beam sweeping signals from the UEs706, 708 and measure or otherwise determine received signalcharacteristics, based upon which the best TRP antenna beam or receptiondirection for each TRP and the corresponding best UE antenna beam ortransmit direction for each TRP connection are identified. The TRPs 702,704 also send to each UE 706, 708 an indication of at least the best UEantenna beam or transmit direction from each UE. Explicit or implicitsignaling could be used for these indications, as described above fordownlink beam sweeping.

In some embodiments, the UEs 706, 708 could also or instead use powercontrol during uplink antenna beam sweeping. For example, power boostingcould be combined with communication resource allocation to boosttransmit power at allocated communication resources for antenna beamtraining. A UE could also or instead apply power nulling to othercommunication resources that have not been allocated for itstransmission of a beam sweeping signal. Such techniques could furtherenable base stations such as the TRPs 702, 704 to identify the bestreception direction for each UE 706, 708 in a multi-connection scenario.

As noted above for downlink beam sweeping, multiple stages of beamsweeping with different beam widths and beam sweeping ranges could beused in uplink beam sweeping.

Uplink beam sweeping as shown in FIG. 7 and described herein could beemployed in other multi-connection embodiments, with only one TRP andmultiple UEs, for example.

Communication resource coordination during downlink or uplink beamsweeping could improve beamforming gain by better aligning beamdirections in a multi-connection scenario. This is discussed in detailabove with reference to the optimal beam group and the optimal beampairs in FIG. 2, but also applies to other embodiments in which beamsweeping signals are transmitted by different transmitters.

After the optimal or preferred antenna beams or directions have beenidentified through downlink or uplink beam sweeping, TRP/UE connectionscan be established. In an embodiment, each TRP-UE pair maintains arecord of designated antenna beams or directions for each connection.With reference to FIG. 4, for example, after the optimal beam pairs forTRP1 and TRP2 are identified, the UE 406 maintains a record of at leastUE beam B1 for a connection to TRP1 402 and UE beam B5 for a connectionto TRP2 404. Similarly, TRP1 402 maintains a record of at least TRP1beam b1 for a connection to the UE 406, and TRP2 404 maintains a recordof at least TRP2 beam b3 for a connection to the UE 406.

Antenna beam/connection records could be in the form of lists or tablesin memory, for example. A beam table or connection table stored by theUE 406 could include a list of UE beam indices for its connected TRPsand the corresponding UE-to-TRP directions for these beams. Otherinformation, such as TRP and/or connection identifiers could also bestored in such tables at UEs. At each of the TRPs 402, 406, a beam tableor connection table could store TRP beam indices for UEs that areconnected to the TRP, the corresponding TRP-to-UE directions for thesebeams, and an identifier of each connected UE. Other information such asUE beam indices for a TRP could also be stored in such a table at a TRP.This could be used, for example, to enable a TRP to send signaling to aUE via control channel, to provide an indication to the UE as to aparticular antenna beam that is to be used for transmission orreception.

In some embodiments, TRPs and UEs maintain multiple transmit and receivebeam indices, and each beam that is identified by a beam indexcorresponds to one connection. In another embodiment, an antenna beamthat is identified by a beam index is used for both transmission andreception. Beam indices are described herein solely for the purposes ofillustration. Other information identifying or indicating beamdirections or beams may be used in other embodiments.

A UE might not be aware of the identity of its serving TRPs, and couldstore a list of just UE beam indices of antenna beams or directions thatare associated with active connections with TRPs. For example, afterinitial beam training, UE beam indices could be assigned to theidentified optimal antenna beams or directions, and mapped to unique andfixed values. Although the best beams or directions for communicationswith a TRP may be updated as a UE is moved or channel conditions changedue to obstacles, for example, when the beams or directions for aconnection are updated, a UE beam index remains unchanged in a fixedindex embodiment.

FIG. 8 is a block diagram illustrating antenna beam management usingfixed beam indices. When the UE 806 is moved between different locationsrelative to TRP1 802 and TRP2 804, the antenna beam directions betweenthe UE and each TRP change. However, in the example shown, the UE beamindex a for the connection between the UE 806 and TRP1 802 and the UEbeam index b for the connection between the UE 806 and TRP2 804 remainthe same after the UE is moved. A fixed beam index maintains a fixedmapping between the UE 806 and the fixed beam index a, b for each TRP802, 804. This could be useful to simplify signaling by each TRP 802,804 to the UE 806 to identify the antenna beam or direction to be usedfor transmitting communication signals after scheduling for aconnection, for example. Although this type of fixed beam index involvesbeam direction updates at the UE 806 when the direction associated witha fixed beam index changes, fixed beam indices may reduce signalingbetween TRPs and UEs. With fixed beam indices, a TRP does not need toknow updated UE beam directions, but rather just the fixed logical UEbeam indices. Fewer bits are used to quantize logical beam indices, ofwhich there are a limited number, when a TRP transmits control channelsignaling to a UE to indicate the particular antenna beam that is to beused by the UE for transmission and reception, for example, relative toa number of bits that would be needed to signal beam directions. Suchcontrol channel signaling may be sent by an LF-TRP, or by an HF-TRPusing wider antenna beams than the highly directional antenna beams thatare used for HF TRP communications.

In another embodiment, beam indices could uniquely correspond to beamdirections. When a UE is moved, beam directions change, and beam indicesalso change. Discrete directions could be specified using a hierarchicalbeam index structure, such as beam index=wide beam index*x+narrow beamindex, with a wide beam index that is modulo x, for example. In anembodiment, x=4. This approach may involve more signaling than a fixedindex approach, because when a UE antenna beam direction changes, the UEsignals updated antenna beam direction to a TRP. More bits are used toquantize antenna beam directions than beam indices when a TRP transmitscontrol signaling to a UE to indicate the particular antenna beam thatis to be used for transmission and reception. As noted above, suchcontrol channel signaling may be sent by an LF-TRP or by an HF-TRP.

Antenna beam management at a TRP could be similar to UE antenna beammanagement. A TRP could use fixed logical beam indices along withcorresponding beam directions, or use beam directions directly as formof beam indices. However, these two options might not involve differentsignaling overhead, because TRPs need not provide a UE with anyindication of the TRP beam indices/directions that are to be used fortransmission and reception by the TRP.

As shown in FIG. 8, movement of the UE 806 may change the preferreddirection for communications between the UE and each TRP 802, 804. Beamtracking may be used to update beam directions for communicationsbetween TRPs and UEs. Beam tracking, after a connection has beenestablished, could use a smaller beam sweeping range and narrowerantenna beams than initial beam training. This is because UEs and TRPsare already at least coarsely beam-aligned after a connection has beenestablished.

With reference to FIG. 7, after initial beam sweeping and alignment,each TRP 802, 804 has multiple TRP-UE beam indices for the multipleconnections to the UEs 706, 708. As in initial beam sweeping, the UEs706, 708 transmit tracking signals for beam tracking in different,orthogonally separated in some embodiments, communication resources.Usage of communication resources by the UEs 706, 708 could be timemultiplexed, with each UE 706, 708 taking turns (periodically) toexecute beam tracking. The TRPs 702, 704 might only perform beamtracking for scheduled UEs in some embodiments. In a non-full bufferscenario, a UE with an empty buffer, that might not be scheduled, couldbe periodically triggered to perform beam tracking. Beam tracking couldbe triggered, for example, by transmitting a beam tracking control orcommand signal from a TRP 702, 704 or another base station to causenon-scheduled UEs to initiate beam tracking.

Time multiplexing of communication resources for beam trackingrepresents one embodiment. FDM or CDM, if a TRP has multiple RF chainsfor example, or a combination of two or more of time, frequency, andcode multiplexing could be used to multiplex communication resourcesduring uplink beam tracking.

In a multi-connection scenario in which a single UE has multipleconnections to different TRPs as in FIG. 4, a UE 406 may have multipleUE-TRP beam indices, and beam tracking preferably involves communicationresource multiplexing for transmission of tracking signals by the TRPs402, 404. TDM, FDM or CDM if the UE 406 has multiple RF chains, or acombination of two or more of these techniques, could be used tomultiplex communication resources during downlink beam tracking.

These beam tracking examples could be applied in joint transmit andreceive tracking, transmit tracking only, and receive tracking only.

Beam tracking, like initial beam training, involves transmission ofsignals in multiple directions and detection of the best directions foreach of multiple connections. Beam tracking signals could be considereda special case of beam sweeping signals, in the sense that both initialbeam training and beam tracking involve transmitting and receivingsignals in multiple directions to sweep a range of directions.

FIGS. 2 to 8 and the descriptions thereof relate primarily to initialbeam training, establishing connections, and beam tracking. Otheraspects of the present disclosure relate to using such connections forcommunications between base stations and UEs.

A UE that has multiple connections to different base stations couldselect one or more of those base stations, or the antenna beam overwhich the connection to such a base station has been established, as ananchor base station or an anchor beam. In an LF-assisted HF system, forexample, a UE could select a preferred anchor LF TRP from among multipleLF-TRPs with which the UE has connections. In an embodiment, the LF TRPor beam associated with a strongest received signal that is detected ata UE during beam sweeping or communications, is selected by the UE as ananchor LF TRP or beam. Similarly, in an HF-only system, a UE couldselect an anchor HF TRP or beam from among multiple HF TRPs or beamsfrom which the UE has connections. One possible selection criterion isthe strongest received signal at the UE.

An anchor TRP could be responsible for such actions as sending controlsignaling to UEs, performing scheduling for a set of TRPs if centralizedscheduling is used in a communication network, and/or coordinating a setof TRPs to distribute data, for example. Control signaling by an anchorTRP could provide such information as beam indices, scheduling grantinformation, and/or acknowledgement/negative acknowledgement (ACK/NACK)information to UEs.

UE-centric assignment or selection of anchor TRPs may be based on theTRP or beam from which a UE receives the strongest signal or associatedwith a highest Signal to Interference-plus-Noise Ratio (SINR) forinstance. An anchor TRP for one UE might not be the anchor TRP foranother UE, and therefore different TRPs may be the anchor TRP fordifferent groups of UEs.

In another embodiment, anchor TRPs are pre-assigned as part of networkconfiguration. Such pre-assignment could be based on geography, forexample, to assign different TRPs or beams as anchor TRPs or beams todifferent parts of buildings or streets. Information that is provided byUEs could be taken into account by TRPs or a network operator indetermining how to assign anchor TRPs. However, in a pre-assignmentembodiment a UE does not decide on its own which TRP is to be the anchorTRP for the UE.

TRPs could also or instead negotiate anchor TRP assignments, based atleast in part on UE feedback for example, and notify UEs of negotiatedTRP assignments.

In some embodiments, LF-TRPs may be preferred as anchor TRPs overHF-TRPs. For example, LF-TRPs might be considered more reliable than HFTRPs for control signaling.

When a UE is moved, the anchor TRP or beam could change. A UE mightreceive a strongest signal from one TRP when it is at one location, butfrom a different TRP when it is moved to a different location. Theanchor TRP could be changed accordingly. In an embodiment in whichanchor TRPs are pre-assigned, for example, anchor TRPs for a UE couldchange based on current location of the UE.

Any of different mechanisms could be implemented for managing datatransmission in embodiments in which a UE has multiple availableconnections to different TRPs. For example, control signaling couldnotify the UE as to the particular receive beam(s) that are to be usedto receive data. An LF TRP in an LF-assisted HF system or an anchor HFTRP, for example, could send control signaling to the UE specifying thereceive beam(s) that should be monitored for data.

Data could also or instead be alternately transmitted to UEs overdifferent beams in a pre-defined manner. For example, with 2 beams, datacould be transmitted in odd Transmission Time Intervals (TTIs) over onebeam and in even TTIs over the other beam. Other patterns are alsocontemplated. If one beam is in better condition than another, based onany of various possible beam condition criteria such as received signalstrength, then more communication resources could be assigned to thebeam that is determined to be in better condition than to the beam thatis determined to be in worse condition.

In such alternate transmission embodiments, there might be no controlsignaling to specify particular beam indices. Control signaling couldinstead specify a transmission or pattern index, for example. Suchcontrol signaling could be transmitted by either an LF TRP inLF-assisted HF system or an anchor HF TRP in some embodiments. However,alternate transmission embodiments may provide less flexibility in beamassignment than embodiments with signaling of beam assignment, becausealternate transmission patterns are pre-defined and certain patternsmight not adapt well to channel condition fluctuations.

UEs could also or instead monitor multiple receive beams at the sametime. If all receive beams are monitored, then no control signalingwould be required to assign beams for UEs to monitor for received data.Beams could even be dynamically assigned for transmission by TRPs inembodiments in which multiple receive beams are monitored. Simultaneousreceive beam monitoring could be implemented, for example, withdifferent RF chains for monitoring different beams. However, such beammonitoring could reduce beamforming gain, in that some monitored beamdirections are effectively wasted if data is being transmitted over onlyone connection with one TRP while a UE monitors all beam directions.

These options, which could also or instead be applied to uplinktransmission from UEs to base stations, are considered in further detailbelow.

FIG. 9 is a block diagram illustrating transmission control according toan embodiment. FIG. 9 is an example of an LF-assisted HF system, with HFTRPs 902, 904, a UE 906, and an LF-TRP 908. In this example, the LF TRP908 sends control signaling, via a control channel such as the PhysicalDownlink Control Channel (PDCCH) for example, to inform the UE 906 as tothe receive beam(s) that it is to monitor for downlink data. The LF TRP908 also communicates with the HF-TRP(s) 902, 904 associated withtransmit beam that is paired with signaled UE receive beam, via an X2interface in the example shown, to inform the HF TRP(s) as to thetransmit beam(s) to be used to transmit data to the UE 906.

FIG. 10 is a block diagram illustrating transmission control accordingto another embodiment, in an HF standalone system that includes HF TRPs1002, 1004 and a UE 1006, without LF TRPs. In this example, the UE 1006receives control signaling from one HF-TRP 1002 (the anchor TRP), butcan receive other transmissions (e.g., downlink data) from either orboth of the TRPs 1002, 1004. Beam switching is performed if the anchorTRP and the transmitting TRP are different. As shown in the example ofFIG. 10, in which the HF TRP2 1004 is the transmitting TRP, controlsignaling is sent from the anchor HF TRP1 1002 to the HF TRP2 1004 viaan X2 interface, to inform the HF TRP2 1004 as to the transmit beam thatis to be used to transmit data to the UE 1006.

In FIGS. 9 and 10, the UE 906, 1006 could receive data over one beam ata time with all receive antenna elements, or multiple beams at a time ifthe UE includes multiple RF chains. For N receive beams, however, eachbeam loses an array gain of −10*log 10(N) dB as compared to using allantenna elements to form a single receive beam.

This type of signaled transmission control may enable dynamic beamassignment, for each time unit such as each TTI for example, butinvolves control signaling of at least the UE downlink receive beam(s).Control signaling of the downlink transmit beam(s) is also sent to thetransmitting HF TRP(s) in an LF-assisted system as in FIG. 9 or when thetransmitting HF TRP in an HF standalone system is not the anchor HF TRPas in FIG. 10.

Uplink transmission could be similarly controlled. The LF-TRP 908 in anLF-assisted HF system or the anchor HF TRP1 1002 could send to the UE906, 1006 uplink scheduling grant information and control informationspecifying the uplink transmit beam(s) to be used by the UE for uplinktransmission. The uplink transmit beam(s) could include a beam that canbe received by either of the HF TRPs 902, 904 or 1002, 1004. In thisexample, uplink transmission is grant-based, and the receiving HF TRP(s)902, 904 or 1002, 1004 already have information regarding the beam(s) towhich the UE 906, 1006 has been granted access. Therefore, there is noseparate control signaling to the receiving HF TRP(s) 902, 904 or 1002,1004 in this example.

FIG. 11 is a block diagram illustrating transmission patterns inaccordance with a further embodiment. In an LF-assisted HF system suchas the system shown in FIG. 9, the LF TRP 908 sends control signaling tonotify the UE 906 and the HF TRPs 902, 904 of a transmission pattern fortransmission of data. In the example shown in FIG. 11, there are twopatterns, and the control signaling in this example includes a patternindex or other information from which the UE 906 and the HF-TRPs 902,904 can determine the transmission pattern that is to be used for acurrent downlink transmission from the HF TRPs to the UE.

In an HF standalone system as shown in FIG. 10, the UE 1006 receivescontrol signaling from the anchor HF TRP1 1002, and can receive othertransmissions (e.g., downlink data) from either or both of the TRPs1002, 1004. The HF TRP2 1004 also receives control signaling, from theanchor HF TRP2 1002, that specifies the transmission pattern that is tobe used. The HF TRPs 1002, 1004 transmit data to the UE 1006 inaccordance with the signaled pattern.

The UE 906, 1006 can receive data over one beam at a time, even if bothbeams are simultaneously scheduled by multiple TRPs 902, 904 or 1002,1004. In a multi-RF chain embodiment, all RF chains could be used for asingle beam at a time to provide high array gain, or the RF chains couldbe used to receive data from multiple beams simultaneously.

Transmission pattern control could involve dynamic assignment of thepatterns via PDCCH, but the periodicity of pattern changes may depend onpattern length. For example, a short pattern could be changed more oftenthan a longer pattern, to adapt to channel condition changes or datatraffic variations. Pattern assignment could instead be semi-static, viaRadio Resource Control (RRC) signaling for example.

Transmission patterns could be equally distributed across multiplebeams, or more weight could be given to particular beams by assigningmore time units to those beams for example.

This transmission control methodology could also or instead be appliedto uplink transmission. The LF-TRP 908 in an LF-assisted HF system as inFIG. 9 or the anchor HF TRP1 1002 in FIG. 10 sends an assigned patternindex or other pattern information in control signaling to the UE 906,1006 for use in uplink transmission to the TRPs 902, 904 or 1002, 1004.

A third transmission control option is also applicable to bothLF-assisted and HF standalone systems. A UE monitors multiple beamssimultaneously, and the UE can receive data from one or multiple beams.At the UE, antenna elements associated with an RF chain form a receivebeam. If there are N RF chains, then up to N receive beams can be formedat the same time. As noted above, however, if there are N receive beams,then each beam loses an array gain of −10*log 10(N) dB as compared withusing all antenna elements to form a single receive beam.

In an embodiment in which the UE is only scheduled by one TRP or fewerthan all TRPs from which it can receive signals, then some of thereceive beams are effectively wasted. Separate RF chains formingseparate receive beams might not be efficient if a UE can only bescheduled by one TRP at a time. It may therefore be preferable to limitthe number of beams to be monitored by a UE, depending upon UEscheduling and/or other UE conditions, for example.

Similarly, for uplink transmission, TRPs may monitor multiple beams, anda UE may transmit using multiple beams.

To summarize the transmission control options described above, signalingof receive and transmit beams may enable flexibility in beam assignment,but involve more control signaling overhead relative to other options.With alternate transmission/reception, there may be less flexibility inbeam assignment relative to signaled beam assignment, but alternatetransmission/reception may involve less control signaling to signal atransmission/reception pattern that receive and transmit beams.Simultaneous monitoring/transmission of multiple beams providesflexibility in beam assignment and lower signaling overhead than theother transmission control methods described above. However, there maybe reduced array gain in forming multiple receive beams compared to theother methods. Time and power may also be wasted in monitoring multiplebeams if transmitters are not transmitting when beams are beingmonitored at a receiver. These embodiments for managing transmissions inmulti-connection scenarios may trade off performance and signaling.

FIG. 12 is a flow diagram illustrating a method according to anembodiment. The example method 1200 involves determining at 1202 acommunication resource that is to be used for transmission of a beamsweeping signal by a communication device. The determined communicationresource is different from communication resources for transmission ofbeam sweeping signals by other communication devices that are within aninterference range of the communication device, as described above withreference to FIGS. 4 and 7, for example. The determination could be madeat 1202 based on received control signaling, for example. An indicationof a beam sweeping communication resource could be stored at acommunication device and accessed before transmitting a beam sweepingsignal, to thereby determine at 1202 the communication resource that isto be used for transmission of the beam sweeping signal.

At 1204, the beam sweeping signal is transmitted using the determinedcommunication resource and multiple antenna beams that are oriented inmultiple directions. The transmission in multiple directions could besimultaneous or sequential. Simultaneous transmission could be performedby communication devices that have multiple RF chains, for example.

The operations illustrated at 1202, 1204 could be performed at a basestation for downlink beam scanning, or at a UE for uplink beam scanning.

In some embodiments, a communication device that transmits a beamsweeping signal at 1204 also monitors at 1206 for receipt of anindication, from another communication device that receives the beamsweeping signal, of a direction from which that other communicationdevice best received the beam sweeping signal. The indication could bean explicit indication of the best reception direction, or an implicitindication from which the first communication device that transmittedthe beam sweeping signal determines the best reception direction.

Other operations may also or instead be performed. For example, aconnection could be established with another communication device thatreceives the beam sweeping signal, via an antenna beam that is orientedin the best reception direction. Connection establishment could involveassigning and/or storing a beam index. In a multi-connection scenario,beam indices could be assigned and stored for each of multiple antennabeams.

Beam tracking as shown at 1210 is another example of an operation thatcould be performed in some embodiments, and could involve repeating thetransmitting at 1204 and the monitoring at 1206, to track movement of acommunication device.

Beam tracking could involve beam scanning in the same direction, uplinkor downlink, as initial beam training, or the opposite direction. Forexample, initial beam training could be performed in the downlinkdirection, by transmitting beam sweeping signals from base stations toUEs, and subsequent beam tracking could be performed in the uplinkdirection, by transmitting beam tracking signals from UEs to basestations. In this case, a base station that transmits a beam sweepingsignal at 1204 could perform beam tracking at 1210 by monitoring themultiple antenna beams for receipt of a beam tracking signal from a UE,and transmit to the UE an indication of a further direction from whichthe base station best received the beam tracking signal from the UE.

Beam indices and/or directions could be updated at 1208 after beamtracking at 1210.

In some embodiments, beam tracking at 1210 is performed periodically.Other embodiments could involve control of beam tracking, by a basestation for example. A base station could transmit to a UE a signal tocause the UE to initiate a beam tracking procedure that involvestransmitting the beam tracking signal from the UE and monitoring at theUE for receipt of the indication of the further direction from the basestation.

FIG. 13 is a flow diagram illustrating an example method according to afurther embodiment. The example method 1300 involves monitoring multipleantenna beams at 1302 to receive beam sweeping signals from othercommunication devices. The antenna beams are oriented in multipledirections. The beam sweeping signals are received from othercommunication devices in different communication resources. For eachcommunication device from which a beam sweeping signal is received, apreferred or optimal beam or direction is determined at 1304, based onthe different communication resources. The preferred beam or directionis a beam or direction from which a received beam sweeping signal isbest received from each communication device.

Feedback could be provided to each communication device at 1306. Forexample, the receiving communication device could determine, for eachother communication device from which a beam sweeping signal isreceived, a transmit direction in which the received beam sweepingsignal was transmitted by the other communication device, and anindication of the determined transmit direction could then betransmitted to the other communication device at 1306. The indicationcould be an explicit indication of the transmit direction from which abeam sweeping signal was best received from each other communicationdevice, or an explicit indication from which each other communicationdevice determines its best transmit direction.

Beam management at a communication device that receives beam sweepingsignals could involve beam indices and/or directions. In embodimentsthat involve beam indices, a beam index for each best direction could beassigned and/or stored at 1308.

In an embodiment, the method 1300 is performed at a UE, and theoperations at 1302, 1304, 1306 are illustrative of downlink beamsweeping and training. Beam tracking at 1310 could be performed in theuplink direction, by transmitting a beam tracking signal from the UEusing the UE antenna beams, and then monitoring at the UE for receipt ofan indication, from a base station, of a further direction from whichthe base station best received the beam tracking signal from the UE.

Uplink beam tracking could be initiated by a UE periodically, or inresponse to command from a base station, for example. The UE couldmonitor for receipt of a signal from a base station to cause the UE toinitiate a beam sweeping procedure, and then, in response to receipt ofsuch a signal, transmit the beam tracking signal and monitor for receiptof the indication from the same base station and/or a different basestation.

Beam indices, directions, or both could be updated at 1308 after beamtracking at 1310.

The example methods 1200, 1300 are intended for illustrative purposes.Other embodiments could involve performing the illustrated operations inany of various ways, performing fewer or additional operations, and/orvarying the order in which operations are performed. For example,antenna beam management in a communication network could involveperforming some of the operations shown in FIGS. 12 and 13 at basestations and performing others of the illustrated operations at UEs.Other variations could be or become apparent to a skilled person basedon the present disclosure.

The embodiments described with reference to FIGS. 12 and 13 relate toexample methods. Apparatus embodiments are also contemplated.

FIG. 14 is a block diagram illustrating an example base station. Theexample base station 1400 includes an antenna array 1402, a beamformer1404 coupled to the antenna array, and a receiver 1406 and a transmitter1408 coupled to the beamformer 1404. The receiver 1406 and thetransmitter 1408 are also coupled to an antenna beam manager 1410, andthe receiver, the transmitter, and the antenna beam manager are coupledto one or more other components generally shown as base station signalprocessing component(s) 1412. A memory 1414 is coupled to the antennabeam manager 1410 and to the base station signal processing component(s)1412. The example base station 1400 also includes one or more networkinterface(s) 1416.

The antenna array 1402 includes multiple antenna elements, and is anexample of a physical interface to a communication medium. The antennaelements could take any of various forms, depending on the type ofcommunication equipment in which the components shown in FIG. 14 areimplemented.

Although shown as a single element in FIG. 14, the beamformer 1404 couldinclude separate receive and transmit beamformers. The beamformer 1404could include gain elements and phase shift elements, for example, toapply gains and phase shifts to antenna feed signals to form differentreceive and transmit antenna beams in different directions.

In some embodiments, the receiver 1406 includes such components as ademodulator, an amplifier, and/or other components of an RF receivechain. The transmitter 1408 may similarly include such components as amodulator, an amplifier, and/or other components of an RF transmitchain.

The antenna beam manager 1410 is implemented using hardware, firmware,one or more components that execute software, or some combinationthereof. Electronic devices that might be suitable for implementing theantenna beam manager 1410 include, among others, microprocessors,microcontrollers, Programmable Logic Devices (PLDs), Field ProgrammableGate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs),and other types of “intelligent” integrated circuits. These electronicdevices are illustrative of circuitry that could be configured to manageantenna beams as disclosed herein. In a processor-based implementation,for example, processor-executable instructions to configure a processorto perform antenna beam management operations are stored in anon-transitory processor-readable medium, such as the memory 1414.

The signal processing component(s) 1412 could similarly be implementedusing hardware, firmware, components that execute software, orcombinations thereof. The number(s) and type(s) of the signal processingcomponent(s) 1412 are implementation-dependent. Any of various types ofsignal processing could be applied to signals that are received by orare to be transmitted by the base station 1400.

The memory 1414 could include one or more solid-state memory devicesand/or memory devices with movable and possibly removable storage media.Illustrative examples of storage media that could be used to implementthe memory 1414 are provided above.

The network interface(s) 1416 could include any of various types ofphysical interfaces to communication media. Like the antenna array 1402,the network interface(s) 1416 could take any of various forms, dependingon the type of communication equipment in which the components shown inFIG. 14 are implemented and the type of communication protocols andmedia that are to be supported.

FIG. 15 is a block diagram illustrating a UE according to an embodiment.The example UE 1500 is similar in structure to the example base station1400 in FIG. 14, and includes an antenna array 1502, a beamformer 1504coupled to the antenna array, a receiver 1506 and a transmitter 1508coupled to the beamformer and to an antenna beam manager 1510, and amemory 1514 coupled to the antenna beam manager. Example implementationsof these components are described above with reference to FIG. 14.Although these components in a UE could be implemented in a similarmanner as in a base station, implementation details could be differentbetween a base station and a UE. A base station, for example, couldinclude a larger antenna array with larger and/or more antenna elementsthan a UE, more memory space than a UE, and/or more powerful processorsthan a UE to implement processor-based components.

Other UE components are generally shown as signal processingcomponent(s) 1512, coupled to the receiver 1506, the transmitter 1508,the antenna beam manager 1510, and the memory 1514. The signalprocessing component(s) could be implemented using hardware, firmware,components that execute software, or a combination thereof. Examples ofsuch implementations are described above.

The example UE 1500 includes one or more input/output (I/O) device(s)1516, such as a display screen, which could be a touchscreen to enableuser input. A separate input device such as a keyboard could also orinstead be provided.

The example base station 1400 and the example UE 1500 are illustrativeof communication devices in which antenna beam management could beimplemented. Both the example base station 1400 and the example UE 1500include an antenna array 1402, 1502 and a transmitter 1408, 1508operatively coupled to the antenna array, to form antenna beams that areoriented in different directions. In the examples shown in FIGS. 14 and15, the transmitters 1408, 1508 control the beamformers 1404, 1504 toform the antenna beams by controlling gains, phase shifts, or both, thatare applied to antenna feed signals associated with the antenna elementsin the antenna arrays 1402, 1502.

The example base station 1400 and the example UE 1500 also include areceiver 1406, 1506 operatively coupled to the antenna array 1402, 1502,and to an antenna beam manager 1410, 1510. The antenna beam manager1410, 1510 is configured to determine a communication resource that isto be used for transmission of a beam sweeping signal, and that isdifferent from a communication resource for transmission of beamsweeping signals by another communication device that is within aninterference range of the communication device. The antenna beam manager1410, 1510 is further configured to transmit the beam sweeping signalvia the transmitter 1408, 1508 using the determined communicationresource and the antenna beams.

Implementing these features in a base station 1400 provides for downlinkbeam sweeping, and implementing these features in a UE provides foruplink beam sweeping.

An antenna beam manager 1410, 1510 could be configured to monitor thereceiver 1406, 1506 for receipt of an indication, from anothercommunication device, of a direction from which that other communicationdevice best received the beam sweeping signal. Such an indication couldbe an explicit indication of the direction or an implicit indicationfrom which the direction can be determined.

Beam sweeping signal reception involves forming receive antenna beamsthat are oriented in different directions. In the example base station1400 and the example UE 1500, the receivers 1406, 1506 are configured tocontrol the beamformers 1404, 1504 to form the receive beams. Either orboth of the antenna beam managers 1410, 1510 could be configured tomonitor the receive antenna beams and receive beam sweeping signals fromother communication devices in different communication resources, and todetermine, for each communication device from which a beam sweepingsignal is received, and based on the different communication resources,a direction from which the received beam sweeping signal is bestreceived. The antenna beam manager 1410, 1510 could be furtherconfigured to determine a transmit direction in which each received beamsweeping signal was transmitted, and to transmit to each communicationdevice an explicit or implicit indication of the determined transmitdirection for that communication device.

After initial beam training, an antenna beam manager 1410, 1510 could befurther configured to perform beam tracking to track movement of a UE.Beam tracking could involve downlink beam sweeping by the base stationantenna beam manager 1410 or uplink beam sweeping by the UE antenna beammanager 1510.

In some embodiments, antenna beam indices are used in beam management.Either or both of the antenna beam managers 1410, 1510 could beconfigured to store to antenna beam indices to the memory 1414, 1514.Antenna beam directions, UE identifiers, TRP identifiers, and/or otherforms of connection identifiers could also or instead be stored to thememory 1414, 1514.

FIG. 16 is a block diagram illustrating a communication device withmultiple RF chains. Base stations, UEs, or both, could include multipleRF chains. The example communication device 1600 includes a digitalcombiner/precoder 1610, multiple RF chains 1620, 1630, and multipleantennas 1624, 1628 and 1634, 1638 coupled to the RF chains throughphase controllers 1622, 1626 and 1632, 1636.

The example communication device 1600 could be implemented as theantenna array, beamformer, receiver, and transmitter in either of bothof FIGS. 13 and 15, for example. A receiver-only implementation of theexample communication device 1600 could include a combiner, and atransmitter-only implementation could include a precoder, instead of thecombiner/precoder 1610.

Two RF chains 1620, 1630 and associated phase controllers 1622/1626,1632/1636 and antennas 1624-1626, 1634/1636 are shown in FIG. 16 by wayof example. In this embodiment, two antenna beams b1, b2 can be formedsimultaneously. Other embodiments could include more RF chains andassociated components to form more than two antenna beams.

A base station such as a TRP could include multiple RF chains to enablesimultaneous transmission/reception of signals over multiple antennabeams in multiple directions during beam sweeping, for example. MultipleTRP RF chains could also or instead be used for simultaneouscommunications with multiple UEs.

A UE that includes multiple RF chains may monitor multiple antenna beamssimultaneously for signals from base stations, and/or simultaneouslytransmit signals over multiple antenna beams in multiple directionsduring beam sweeping.

For a UE implementation, consider an example in which a UE is connectedto multiple TRPs, but can be scheduled by only one TRP at a time. InDynamic Point Selection (DPS) of centralized Coordinated Multi-Point(CoMP), for example, because of channel hardening under massive MultipleInput Multiple Output (mMIMO), UE scheduling at a TRP becomes wideband,and a UE can only be scheduled by one TRP at a time. In this case, a UEcould include only one RF chain to form all antenna beams, in onedirection at a time. A UE that includes multiple RF chains could use anyone of the multiple RF chains to form one antenna beam at a time, ormore than one RF chain could be used to simultaneously form more thanone antenna beam in the same direction.

In UE-centric distributed CoMP, for example, UE scheduling at each TRPis independent, and therefore a UE that is connected to multiple TRPscould be scheduled by multiple TRPs at a time. A UE that has at least asmany RF chains as TRP connections may simultaneously receive downlinkdata transmissions from multiple TRPs, by forming multiple antenna beamsfor the TRP connections using different RF chains.

What has been described is merely illustrative of the application ofprinciples of embodiments of the present disclosure. Other arrangementsand methods can be implemented by those skilled in the art.

The contents of the drawings are intended solely for illustrativepurposes, and the present invention is in no way limited to theparticular example embodiments explicitly shown in the drawings anddescribed herein. For example, FIG. 1 is a block diagram of acommunication system in which embodiments may be implemented. Otherembodiments could be implemented in communication systems that includemore base stations than shown, or that have different topologies thanthe example shown. Similarly, the examples in the other drawings arealso intended solely for illustrative purposes.

In addition, although described primarily in the context of methods andsystems, other implementations are also contemplated, as instructionsstored on a non-transitory processor-readable medium, for example. Theinstructions, when executed by one or more processors, cause the one ormore processors to perform a method.

The previous description of some embodiments is provided to enable anyperson skilled in the art to make or use an apparatus, method, orprocessor readable medium according to the present disclosure. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles of the methods anddevices described herein may be applied to other embodiments. Thus, thepresent disclosure is not intended to be limited to the embodimentsshown herein but is to be accorded the widest scope consistent with theprinciples and novel features disclosed herein.

The present disclosure encompasses, among others, embodiments in which amethod involves: receiving at a communication device, using a pluralityof antenna beams that are oriented in a plurality of directions, a firstbeam sweeping signal from a first transmitting communication device in afirst communication resource and a second beam sweeping signal from asecond transmitting communication device in a second communicationresource that is different from the first communication resource;determining, based on the first communication resource, a firstdirection of the first beam sweeping signal; and determining, based onthe second communication resource, a second direction of the second beamsweeping signal. For example, the first direction could be a directionof the plurality of directions from which the first beam sweeping signalis best received from the first transmitting communication device, andthe second direction could be a direction of the plurality of directionsfrom which the second beam sweeping signal is best received from thesecond transmitting communication device.

Such a method could also include determining, based on the firstcommunication resource, a first transmit direction in which the firstbeam sweeping signal was transmitted by the first transmittingcommunication device; determining, based on the second communicationresource, a second transmit direction in which the second beam sweepingsignal was transmitted by the second transmitting communication device;and transmitting an indication of the first transmit direction to thefirst transmitting communication device and an indication of the secondtransmit direction to the second transmitting communication device.

The first indication could be an explicit indication of the firsttransmit direction, and the second indication could be an explicitindication of the second transmit direction. In another embodiment, thefirst indication is an implicit indication from which the firsttransmitting communication device determines the first transmitdirection, and the second indication is an implicit indication fromwhich the second transmitting communication device determines the secondtransmit direction.

The communication device is a UE in some embodiments, and a method couldinclude transmitting a third beam tracking signal from the UE using theplurality of antenna beams; and monitoring, at the UE, for receipt of anindication, from a base station, of a further direction of the pluralityof directions from which the base station best received the third beamtracking signal from the UE. The method could also involve, beforetransmitting the third beam tracking signal from the UE: monitoring, atthe UE, for receipt of a signal, from the base station, to cause the UEto initiate a beam sweeping procedure that comprises transmitting thethird beam tracking signal from the UE and monitoring for receipt of theindication of the further direction from the base station.

A non-transitory processor-readable medium could be used to storeinstructions which, when executed by one or more processors, cause theone or more processors to perform a method that involves: receiving at acommunication device, using a plurality of antenna beams that areoriented in a plurality of directions, a first beam sweeping signal froma first transmitting communication device in a first communicationresource and a second beam sweeping signal from a second transmittingcommunication device in a second communication resource that isdifferent from the first communication resource; determining, based onthe first communication resource, a first direction of the plurality ofdirections from which the first beam sweeping signal is best receivedfrom the first transmitting communication device; and determining, basedon the second communication resource, a second direction of theplurality of directions from which the second beam sweeping signal isbest received from the second transmitting communication device.

A further embodiment relates to a communication device that includes: anantenna array; a transmitter, operatively coupled to the antenna array;a receiver operatively coupled to the antenna array, to form a pluralityof antenna beams that are oriented in a plurality of directions; and anantenna beam manager, operatively coupled to the transmitter and to thereceiver, to: receive, using the plurality of antenna beams, a firstbeam sweeping signal from a first transmitting communication device in afirst communication resource and a second beam sweeping signal from asecond transmitting communication device in a second communicationresource that is different from the first communication resource;determine, based on the first communication resource, a first directionof the first beam sweeping signal; and determine, based on the secondcommunication resource, a second direction of the second beam sweepingsignal. As described above, the first direction could be a direction ofthe plurality of directions from which the first beam sweeping signal isbest received from the first transmitting communication device, and thesecond direction could be a direction of the plurality of directionsfrom which the second beam sweeping signal is best received from thesecond transmitting communication device.

The communication device could be implemented as a UE, and the firsttransmitting communication device and the second transmittingcommunication could be base stations.

The antenna beam manager is further configured, in some embodiments to:determine, based on the first communication resource, a first transmitdirection in which the first beam sweeping signal was transmitted by thefirst transmitting communication device; determine, based on the secondcommunication resource, a second transmit direction in which the secondbeam sweeping signal was transmitted by the second transmittingcommunication device; and transmit via the transmitter an indication ofthe first transmit direction to the first transmitting communicationdevice and an indication of the second transmit direction to the secondtransmitting communication device.

The first indication could be an explicit indication of the firsttransmit direction, and the second indication could be an explicitindication of the second transmit direction. In another embodiment, thefirst indication is an implicit indication from which the firsttransmitting communication device determines the first transmitdirection, and the second indication is an implicit indication fromwhich the second transmitting communication device determines the secondtransmit direction.

The antenna beam manager could be further configured to perform beamtracking to track movement of the UE.

The communication device could include: memory, operatively coupled tothe antenna beam manager, and the antenna beam manager could be furtherconfigured to store to the memory a first beam index associated with thefirst direction and a second beam index associated with the seconddirection.

We claim:
 1. A method comprising: determining a first communication resource to be used for transmission of a first beam sweeping signal by a first communication device, the first communication resource being different from a second communication resource for transmission of a second beam sweeping signal by a second communication device that is within an interference range of the first communication device; and transmitting the first beam sweeping signal from the first communication device using the first communication resource and a plurality of antenna beams that are oriented in a plurality of directions.
 2. The method of claim 1, further comprising: monitoring, at the first communication device, for receipt of an indication, from a third communication device that receives the first beam sweeping signal, of one direction of the plurality of directions from which the third communication device best received the first beam sweeping signal.
 3. The method of claim 2, wherein the indication comprises an explicit indication of the one direction.
 4. The method of claim 2, wherein the indication comprises an implicit indication from which the first communication device determines the one direction.
 5. The method of claim 2, further comprising: establishing a connection with the third communication device via an antenna beam of the plurality of antenna beams that is oriented in the one direction.
 6. The method of claim 5, wherein the first communication device comprises a base station and the third communication device comprises User Equipment (UE), the method further comprising: repeating the transmitting and monitoring to track movement of the UE.
 7. The method of claim 5, wherein the first communication device comprises a base station and the third communication device comprises User Equipment (UE), the method further comprising: monitoring, at the base station, the plurality of antenna beams for receipt of a third beam tracking signal from the UE; and transmitting to the UE an indication of a further direction from which the base station best received the third beam tracking signal from the UE.
 8. The method of claim 7, further comprising, before monitoring the plurality of antenna beams for receipt of the third beam tracking signal from the UE: transmitting to the UE a signal to cause the UE to initiate a beam tracking procedure that comprises transmitting the third beam tracking signal from the UE and monitoring at the UE for receipt of the indication of the further direction from the base station.
 9. The method of claim 1, wherein the first communication resource and the second communication resource comprise a set of orthogonal communication resources.
 10. The method of claim 1, wherein the first communication resource and the second communication resource comprise a set of time division multiplexed communication resources, a set of frequency division multiplexed communication resources, or a set of code division multiplexed communication resources.
 11. A non-transitory processor-readable medium storing instructions which, when executed by one or more processors, cause the one or more processors to perform a method comprising: determining a first communication resource to be used for transmission of a first beam sweeping signal by a first communication device, the first communication resource being different from a second communication resource for transmission of a second beam sweeping signal by a second communication device that is within an interference range of the first communication device; and transmitting the first beam sweeping signal from the first communication device using the first communication resource and a plurality of antenna beams that are oriented in a plurality of directions.
 12. A communication device comprising: an antenna array; a transmitter, operatively coupled to the antenna array, to form a plurality of antenna beams that are oriented in a plurality of directions; a receiver operatively coupled to the antenna array; and an antenna beam manager, operatively coupled to the transmitter and to the receiver, to: determine a first communication resource to be used for transmission of a first beam sweeping signal by the communication device, the first communication resource being different from a second communication resource for transmission of a second beam sweeping signal by a second communication device that is within an interference range of the first communication device; and transmit the first beam sweeping signal via the transmitter using the first communication resource and the plurality of antenna beams.
 13. The communication device of claim 12, implemented as a base station.
 14. The communication device of claim 12, wherein the antenna beam manager is further configured to monitor the receiver for receipt of an indication, from a third communication device that receives the first beam sweeping signal, of one direction of the plurality of directions from which the third communication device best received the first beam sweeping signal.
 15. The communication device of claim 14, wherein the indication comprises an explicit indication of the one direction.
 16. The communication device of claim 14, wherein the indication comprises an implicit indication from which the communication device determines the one direction.
 17. The communication device of claim 14, wherein the communication device is implemented as a base station and the third communication device comprises User Equipment (UE), and wherein the antenna beam manager is further configured to perform beam tracking to track movement of the UE.
 18. The communication device of claim 14, further comprising: memory, operatively coupled to the antenna beam manager, wherein the antenna beam manager is further configured to store to the memory a beam index associated with the one direction. 